The invention pertains to an absorption cooling device for operating a thermodynamic cooling circulation such that the cooling circuit takes heat from a space to be cooled. Such a cooling device traditionally e.g. is used for cooling down a refrigerator section of a household refrigerator or the like as compared to an environment.
In a cooling device operated under the traditional so-called absorption method a working substance, in most cases ammonia soluble in a solvent, mostly water, is applied in the circuit. This circuit includes an expeller also referred to as cooker or pump, a condenser, an evaporator and an absorber. In the expeller the working agent out of solvent enriched with the working agent is expelled with supply of external energy by e.g. a radiator. In gaseous condition the working agent is transferred from the expeller to the condenser where the working agent conveys heat to the environment, cools down and finally condenses. The condensed working agent is transferred from the condenser to the evaporator where it evaporates with absorbing heat on a low level, e.g. in the evaporator of a refrigerator, and in gaseous condition is transferred to the absorber. In the absorber the working agent is absorbed in the solvent under emission of heat and then is returned to the expeller in a form dissolved in the solvent, the described working agent circuit being closed thereby.
Since the transport of the working agent from the absorber to the expeller is effected in a form dissolved in the solvent and the solvent which due to the effect of the expeller is enriched in working agent, again is transferred to the absorber for there being enriched with working agent a so-called solvent circuit exists between expeller and absorber.
In the solvent circuit solvent loaded with working agent in liquid form is fed to the expeller via a connecting line or similar, the connecting line being connected to a reservoir subsequent to the absorber. Using this reservoir the working agent can be filled into the working agent circuit. Due to gravity the solvent accumulates as liquid volume in the reservoir, wherein in correspondence to the amount of solvent volume a liquid level or a liquid surface, respectively, of said solvent volume is formed. Below said liquid level the solvent exists in liquid form together with the working agent dissolved therein, while above said liquid level a gas atmosphere is existent of gaseous solvent, working agent and, if applicable, an assistant gas for operation of the working agent circuit and further gases.
To the described liquid volume the solvent enriched with working agent is supplied from the absorber, the solvent enriched with working agent penetrating the liquid level as continuous trickle or drop-by-drop and thus merging into the liquid level existing on low level. The reservoir, therefore, does not only takes in a substantial portion of the working medium in order to keep it on store for the working agent circuit but also makes available absorber surface for a residual absorption for the circuit by the enlarged surface. Finally, it serves as level balance for the filling level in the expeller and establishes the connection of expeller, evaporator, absorber and, if applicable, condenser as well as siphon pipe.
In spite of the fact that the known apparatus per se works satisfactorily, it nevertheless turned out that the construction comprises drawbacks due to system and construction. Thus, a large portion of the working medium is stored in the reservoir without functional effect for step by step being supplied to the expeller. A substantial portion of the liquid in the reservoir does not participate in the proper absorption but only serves for a residual absorption in insufficient degree. By the functional separation of the working medium into an active and inactive portion a substantial demand for a larger total volume of coolant is given, this resulting in an increased portion of ecologically noxious ammonia and chromate portions, which also cause problems in terms of waste disposal. Finally, the above-described apparatus requires an expensive constructional harmonization between the reservoir and the expeller in order to make available a suitable liquid level. For receiving a large liquid volume and for making available a large absorption and cooling surface the reservoir must be of large volume and, therefore, beside its terminals for the different components of the unit like absorber, evaporator, expeller and condenser, siphon pipe and filling valve comprises numerous welding seam connections so that the danger of leakages is increased.
The invention, therefore, is based on the object of improving an absorption cooling device of the known kind such that with equal cooling power reduced storing of coolant is required and, thus, simultaneously waste disposal expense is reduced. Said device in addition is to require lower constructional expense and be cheaper manufacturable with lower weight at the same time.
The invention herein starts on an absorption cooling device with
an expeller for expelling a working agent in gaseous form of enriched solvent for depleting said working agent in a solvent circuit,
a first connecting line for transferring the expelled working medium from said expeller to a condenser for condensing said expelled working agent,
a second connecting line for transferring said condensed working agent from said condenser to an evaporator for evaporating said condensed working agent with absorption of heat from a surface to be cooled,
a third connecting line for transferring said evaporated working agent from said evaporator to an absorber unit,
a fourth connecting line for transferring said solvent depleted of working agent from said expeller to said absorber unit, wherein said absorber unit comprises a counterflow exchange path extending over a predefined level difference, into which ends said third connecting line on a low level and into which ends said fourth connecting line on a high level so that said working agent in said solvent enriches in said absorber unit,
a fifth connecting line for transferring said solvent enriched with working agent from said absorber to said expeller.
Herein, at least a part of said fifth connecting line is filled with a liquid portion of said solvent and in an area of the end of said fifth connecting line, facing said expeller or in said expeller itself a first liquid level of said solvent is formed, a corresponding second liquid level communicating with said first liquid level through said fifth connecting line being formed.
A first aspect of the invention is based on the conception of dimensioning the total surface of said second liquid level comparatively small and of reducing the total volume of said working agent in that only an active portion of said working agent is used in the absorption process and not an inactive portion is used for storing. As will be explained later, thereby the constructional leveling of said liquid level to said expeller can be achieved in simple manner. The system only must be filled with the amount of working medium (ammonia, water, inhibitor) required for creating said absorption process. This results in the advantages that the amount of operating substances/noxious matter ammonia, water, corrosion inhibitor is reduced and thus also the problems created in connection with a later waste disposal (costs, danger potential) are reduced. By a smaller total volume costs and weight can be saved and by the direct introduction of the absorbing working medium into the heat exchanger the corresponding absorption heat is utilized better. Finally, operating safety (resistance to pressure) is increased in that in relation to traditional absorption cooling devices less welding connections are used.
In case of smaller embodiment of said total surface of said second liquid level an amount of solvent enriched with working agent, directly supplied from said absorber to at least a part of said total surface causes a comparatively large change of working agent concentration in said solvent directly below said second liquid level. Thereby, in particular during the starting phase of said cooling device, when changes in concentration of said working agent in said solvent occur regularly, said changes in concentration quickly are transferred to the solvent again supplied to said expeller so that to a great extent a direct change to the stationary operating condition is possible.
It turned out to be advantageous to refer said total surface of said second liquid level to a correspondingly determined medium cross-section of said fifth connecting line or said fourth connecting line. Herein, it is advantageous in particular to embody said total surface of said second liquid level smaller than ten times, in particular smaller than eight times, in particular smaller than five times, in particular smaller than three times and in particular smaller than twice said medium cross-section. In particular, said total surface of said second liquid level can also be embodied approximately equal to said cross-section.
Herein, it is possible that said total surface of said second liquid level is composed of several partial surfaces each correspondingly completely encircled, of said second liquid level, which are created within spatially separated components of said cooling device on mutually corresponding level.
In accordance with a second aspect the invention also is characterized in that said second liquid level is encircled by at least one or several of said components of a group of components which includes said fifth connecting line, namely in an area of an end thereof facing said absorber, said absorber and said third connecting line, namely in an area of an end facing the entry into said absorber. By this measurement the shape of said second liquid level also is determined by the shape of the components of this group.
Herein, the shape of these components themselves is designed with respect to the function intended for the respective component, for operation of said cooling device. This means that the cross-sections of said third and fifth connecting lines are designed such that said connecting lines optimally fulfill their function for transferring said evaporated working agent from said evaporator to said absorber unit and/or for transferring, respectively, said solvent enriched with working agent from said absorber to said expeller with respect to operating conditions and manufacturability of said cooling device. The same is true for said absorber which essentially is designed for making available a counterflow exchange path where said working agent in said solvent is enriched.
This results in that said second liquid level is formed in components of said cooling device, which are not dimensioned with respect to a large total surface of said liquid level, as was the case in traditional cooling systems in which said second liquid level is formed in a component in terms of function completely different from said components of said above-cited group of components, namely a reservoir for said solvent.
Preferably, no further components but only the components of said group take part in the encircling of said second liquid level.
In spite of the fact that with the cooling device a comparatively quick reaching of the stationary operating condition is possible, nevertheless, changes in height or level, respectively, of said first and/or second liquid level, respectively, are possible during the starting phase of said cooling device. In particular, the level of said first and/or second liquid level, respectively, can drop during the starting phase of said cooling device.
Preferably, the amount of solvent as well as the amount of working agent is dimensioned such that the entire surface of said second liquid level is encircled by said fifth connecting line at least during the stationary operation of said cooling device.
Alternatively, also preferably the surface of said second liquid level can be encircled by said absorber at least during the stationary operation of said cooling device.
Herein, said counterflow exchange path of said absorber preferably includes a pipe extending obliquely to horizon, in which the solvent supplied to said absorber on high level trickles down and therein enriches with working agent. Said pipe can then in advantageous manner serve for encircling of said second liquid level.
Alternatively, it is provided for in advantageous manner that said pipe of said counterflow exchange path in one piece extends in a pipe extension out of said counterflow exchange path such that said pipe extension encircles the surface of said second liquid level. Said pipe extension herein can be connected without seam and with formation of a welding or brazing point to the proper pipe of said counterflow exchange path.
Preferably, the amount of liquid in said cooling device is dimensioned such that during the starting phase of the operating of the device said second liquid level is encircled by said third connecting line. Herein, said liquid level can drop during operation of the device so that he then will assume the above-described level later and transfer of said evaporated working agent into said absorber unit can take place in uninhibited manner as well.
With respect to a simple manufacture said third connecting line for supplying said evaporated working agent from said evaporator to said absorber unit ends in the pipe extending obliquely to horizon, in a position where said pipe extends on both sides of said connecting point, in straight line essentially in particular. Thereby, the connection between said pipe and said third connecting line can simply be embodied in form of a T-member, the horizontal beam of said xe2x80x9cTxe2x80x9d being aligned with said pipe and said vertical beam of said xe2x80x9cTxe2x80x9d being aligned with the end of said third connecting line.
Herein, preferably also in respect to a simple manufacturability said fifth connecting line for transferring said solvent enriched with working agent from said absorber to said expeller is coupled to said absorber such that said fifth connecting line directly ends in said pipe of said counterflow exchange path or an extension thereof.
Furthermore, said absorption cooling device preferably is operated with an assistant gas supporting the transfer of said working agent in its gaseous form. In respect thereto, preferably a sixth connecting line for transferring said assistant gas from said absorber to said evaporator is provided for, said sixth connecting line ending in said evaporator on a high level.
Furthermore, with respect to a good energetical efficiency of said cooling device a liquid heat exchanger is provide for in which said fourth connecting line and said fifth connecting line extend in areas with formation of a counterflow heat contact one beside the other.
In order to achieve that the absorption surface of said absorption cooling device approximately corresponds to the absorption surface of a device with a reservoir, care is taken in accordance with a further preferred feature of the invention that said absorption surface of said reservoir in case of unchanging total absorption surface by increasing the absorption surface of said counterflow exchange path of said absorber unit is integrated into it. This can be effected in advantageous manner in that said absorption surface of said reservoir by extension of said counterflow exchange path of said absorber unit is integrated into it or that said absorption surface or that said absorption surface of said reservoir by enlargement of cross-section of said pipeline of said counterflow exchange path of said absorber unit is integrated into it or that said absorption surface of said reservoir by enlargement of the surface of said inside wall of said pipeline of said counterflow exchange path of said absorber unit is integrated in it by means of grooves arranged in said wall. Said grooves advantageously can extend in two different directions and cross correspondingly.